Reservoir computing as a highly efficient architecture for recurrent neural networks has been implemented in a variety of ways, including anharmonic oscillators, liquid surfaces, and optical and electronic circuits.
Here, we investigate whether active particle networks that mimic fundamental dynamical processes of living systems can serve as reservoirs. In particular, we realize active particle oscillators, each consisting of an immobile and an active colloidal microparticle suspended in a layer of a liquid solution. The motion of the active particles is manipulated by a feedback system using a focused laser that stimulates the particles to float in 2D by thermophoresis [1]. The active particle is programmed to be attracted to the immobile particle with a delayed response that exhibits a pitchfork bifurcation, which introduces nonlinearity and memory into the response of a single active oscillator.
Using time multiplexing, the propulsion of the oscillator is selected at different times as virtual nodes of a reservoir that are coupled to an input layer. Since the motion of the active particle is affected in a nonlinear manner with a memory of its previous state, the last node state is naturally coupled to the other nodes from different iterations due to the intrinsic property of the delayed oscillator. We illustrate the performance of the reservoir consisting of multiple oscillators with different delays by the tasks of nonlinear prediction and classification.
[1]. F. Martin et al. ACS Nano 15, 2, 3434-3440 (2021)
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